This invention relates to a portable transducer simulator for use in the development and/or maintenance of instrumentation circuitry in automotive vehicles.
Automotive vehicles contain instrumentation circuits which present information to the vehicle operator concerning operating conditions of the vehicle. In large trucks such as highway tractors there are a substantial number of instrumentation circuits which present information about the operating conditions of various parts of the powertrain, such as, for example, engine oil pressure, engine oil temperature, coolant temperature, transmission fluid temperature, etc.
Each circuit is operated by a transducer, or sensor, which is physically disposed on the vehicle at an appropriate location to monitor the condition of interest. Each transducer develops an electrical signal indicative of the condition of interest. These signals are conducted through various wiring harnesses of the vehicle to appropriate instrumentation, such as, for example, electronic read-outs or electrical gages, on the vehicle's instrument panel. In this way the values of the monitored conditions are presented to the vehicle operator.
The ability to simulate the various transducers may be advantageous in the diagnostic checking of a vehicle's instrumentation circuitry. For example, the ability to check a temperature instrumentation circuit without having to warm up and cool down a vehicle can yield considerable savings in time and labor.
The availability of many different vehicle models and optional accessories has complicated diagnostic testing from the standpoint of compatability of test equipment with vehicles. The availability of many different models and accessories has spawned numerous different physical configurations for the electric circuit terminations of wiring harnesses and electrical devices, even though the same circuits in different vehicles may be essentially electrically identical. Moreover, the increased use of electronic instrumentation in a vehicle has increased the need for diagnostic testing, and equipment which will serve this end is becoming increasingly important, particularly where it is not overly complex and can be expeditiously used for diagnosis.
The present invention relates to a portable transducer simulator which is well-suited for compatability with different vehicle models and accessories in simulating one or more actual transducers for the expeditious checking of a vehicle's instrumentation circuitry. These attributes are embodied in apparatus which comprises a small portable transducer simulator unit and a number of adapter cables each of which serves to adapt the unit for connection into a particular vehicle wiring harness in substitution of one or more of the vehicle's transducers which operate the vehicle's instrumentation circuitry.
The unit comprises a compact case which contains resistance values representative of typical transducer resistance values for various transducer operating conditions. It also has a rotary selector switch which the user operates to select particular resistance values for presentment to the instrumentation circuitry when the simulator unit is connected to the vehicle instrumentation circuitry via the appropriate adapter cable in substitution of the actual transducer being simulated. Presentment of known resistance values to the instrumentation circuitry enables the response of the circuitry to known inputs to be ascertained. The disclosed embodiment possesses the ability to simulate both temperature and pressure transducers so that pressure and temperature circuits can be quickly and reliably checked. Moreover, the specific arrangement of the temperature and pressure simulating capabilities in the unit is especially conducive to facile and expeditious usage.
The foregoing features, advantages, and benefits of the invention, along with additional ones, will be seen in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings, in which like reference numerals designate like parts, portray a presently preferred embodiment of the best mode contemplated in carrying out the invention.